The United States has "a long tradition of welcoming refugees," and it expects to welcome thousands more of them from Syria in 2015 and 2016, despite concerns about foreign fighters, the State Department said.

"The United States has admitted 524 Syrians since 2011. We’re likely to admit 1,000 to 2,000 Syrian refugees for permanent resettlement in Fiscal Year 2015 and a somewhat higher number, though still in the low thousands, in Fiscal Year 2016," spokeswoman Jen Psaki told reporters on Friday.

But at a hearing of the House Homeland Security Committee last week, Chairman Mike McCaul (R-Texas) said it would be a "huge mistake" to bring refugees from Syria and Turkey into the United States where they "could potentially be radicalized."

Psaki told reporters on Friday that national security "is absolutely a priority" in the decision to admit refugees.

"That’s why the process can take months, if not longer. And we have a lot of experience with this with Afghanistan, with Iraq, with Somalia, and other places where the United States has taken refugees in from.

"Refugees are the most carefully vetted of all travelers to the United States," Psaki continued.

"Every refugee under consideration for admission to the United States undergoes the same intensive security screening involving multiple federal intelligence, security, and law enforcement agencies. These include the NCTC, the Terrorist Screening Center, the Department of Defense, the FBI. This process includes a lengthy overseas in-person refugee determination and security screening interview conducted by...specially trained DHS officers.

Psaki repeated that "one of our values is bringing in and welcoming refugees who have fled horrors around the world, and that continues to be central to what we believe in."

In response to a question, Psaki said she's aware of only "two incidents" involving "two Iraqis" who were admitted to Kentucky and were later accused of trying to send weapons and money to al Qaida in Iraq.

"Additional measures were activated as a result of evidence that came in on two Iraqis after they were admitted to Kentucky. Those measures are now applied to all refugees. So we always evaluate and use information as it becomes available," Psaki said.

At the Feb. 11 hearing, McCaul said he's written a letter to National Security Adviser Susan Rice expressing his concern about refugees from Syria and Turkey:

"I've been over there and I've seen them. Yeah, most of them are women and children, but there are male actors that concern me. I think this would be a huge mistake if we bring in these (refugees) into the United States that could potentially be radicalized...We're not only trying to keep these guys, the foreign fighters, out, but under this would be a -- a federally sanctioned welcome party, if you will, to potential terrorists in the United States."

Nicholas Rasmussen, the director of the National Counterterrorism Center, told McCaul that the Syrian refugees are "clearly a population of concern."

Rasmussen and two other witnesses told the committee that a rigorous vetting and screening process is applied to all refugees in an attempt to identify possible connections to foreign terrorist groups.